I found this build while playing around in pre season 12 and it does ALOT of damage.
You are trading your poke damage early game for a huge mid game.

The reworked Cosmic Drive gives you 40 and 20% move speed if you hit 3 different abilities/attacks on an enemy. You will almost always proc this even without your ult, this gives you an extra edge and the movement speed helps you escape any counterattacks.

The new item Shadowflame Gives zyra magic pen which makes her spells hit extra hard against squishy targets and it gives you more magic pen against shielded enemys.

Those 2 items together with a Luden's Tempest will make sure you one shot most squishy champs in 1 combo. If they do have alot of tanks you can go for a Liandry's Torment instead.

You do need to watch out in your early levels because the absence of comet means any mage will outtrade you in lane.

Enjoy playing this build i found, i might update this later if i find anything else.